How to prevent and treat chrysanthemum powdery mildew "Chrysanthemum Powdery Mildew Prevention and Treatment Guide"

How to prevent and treat chrysanthemum powdery mildewThese do you know? Small experience of the flower clinic with chrysanthemum, how to prevent and treat chrysanthemum powdery mildew, let's take a look together.Powdery mildew is a common disease on chrysanthemum, widely occurring in various planting areas across the country, severely affecting the yield and quality of chrysanthemum.Chrysanthemum powdery mildewSymptoms: Initially, light yellow small spots appear on the leaves, which gradually expand, and the affected leaves are covered with white powdery mold-like substances, which are the mycelium and conidia of the pathogen. In severe cases, the leaves become twisted and deformed or turn yellow and fall off, the diseased plants develop poorly, and become dwarfed.Pathogen: Erysiphe cichoracearum DC., known as the chrysanthemum powdery mildew, belongs to the Ascomycetes subphylum of fungi. The mycelium grows on both sides of the leaves, the conidia are nearly cylindrical to barrel-shaped, and are串联. The closed ascocarps are oblate spheroidal, with many appendages, dark brown, measuring 90-130 μm, containing 10-20 asci; the asci are oval, oblong to elliptical, measuring 20-28×14-18 (μm), each ascus usually contains 2 ascospores, occasionally 3; elliptical, measuring 19-38×11-22 (μm). In southern China, the sexual state is generally not produced, and the asexual state is Oidium chrysanthemi Rabenh.Incidence characteristics: In the north, the pathogen overwinters in the form of closed ascocarps with the diseased residues on the soil surface, and the following year, ascospores are released for initial infection. After the disease occurs in the field, conidia are produced on the mycelium of the affected parts for reinfection. In the south or in greenhouse conditions in the north, the pathogen overwinters in the form of mycelium on the host, and produces conidia when conditions are suitable, which are spread by air currents. Sometimes, the infection threads produced by the germination of spores directly invade the epidermal cells of the host, forming absorbent organs to absorb nutrients inside the epidermal cells. The mycelium mostly grows on the surface of the host, forming attachment organs at many places, and forming closed ascocarps in late autumn or overwintering in the form of mycelium on the host. Cold and humid conditions in spring and autumn are prone to disease.Control methods:1. Agricultural control: Fields should not be planted too densely, and attention should be paid to ventilation and light; scientific fertilization and water management, applying more phosphorus and potassium fertilizers, timely irrigation, and improving the disease resistance of plants; removing diseased leaves and residues in winter and deeply burying or burning them.2. Chemical control: Start spraying 36% methyl thiophanate suspension 500 times liquid, or 60% Fungicide Baobao No. 2 water-soluble powder 800 times liquid, 40% Dakening suspension 600-700 times liquid, 47% Jarinon wettable powder 700-800 times liquid, or 20% Triadimefon emulsion 1500 times liquid, every 7-10 days, for 2-3 consecutive treatments. For severe cases, 25% Dalituo emulsion 4000 times liquid or 40% Fuxing emulsion 9000 times liquid can be selected.Commonly used fungicides: Methyl thiophanate, Fungicide Baobao, Dakening, Jarinon, Triadimefon, Dalituo, FuxingThe above information introduces the experience and knowledge of how to prevent and treat chrysanthemum powdery mildew. I hope this article can bring you some help!